Androgens are selectively retained by target cells where androgens translocate to the cell nucleus, influence chromatin, allowing the transcription of RNA which results in increased protein synthesis. Androgen-responsive cultured cells provide an excellent model system in which to study the mechanisms of action of androgens independently of other hormones and tissues. Cultured chick comb cells will be exposed to various androgens after which the following biochemical events will be measured: cell proliferation; rates of protein, RNA, DNA, collagen and hyaluronic acid synthesis; ornithine decarboxylase, RNA polymerase and chromatin template activities; and levels of androgen receptors. These parameters will be used to investigate factors which regulate the relative potencies of various androgens in this tissue. Studies of messenger RNA synthesis and translational parameters of protein synthesis will be correlated with changes in cellular morphology and the other biochemical parameters after androgen treatment.